<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <!-- 我是注释 -->
  我是文本,呵呵呵
  <div class="box">哈哈哈</div>
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
  </ul>
  <script>
    var bodyEl = document.body
    // 根据body元素去获取子元素
    var childElements = bodyEl.children
    console.log(childElements)

    // 获取box元素
    var boxEl1 = bodyEl.firstElementChild
    var boxEl2 = bodyEl.children[0]
    console.log(boxEl1, boxEl2, boxEl1 === boxEl2)

    // 获取ul,li元素
    var ulEl = boxEl1.nextElementSibling
    console.log(ulEl)
    var liEl = ulEl.children
    console.log(liEl)

  </script>
</body>

</html>